No One Knows Exactly How Many eBooks Indie Authors Published Last Year, Much Less ISBNs

In our next trip behind the publishing industry curtain, we are going to take a look at Bowker’s annual report on ISBN registrations and discuss how everyone is still misunderstanding the annual statistics.

I’m sure we all w the story in PW last week:

A new report issued by Bowker found that a total of 786,935 ISBNs were issued to self-published authors in 2016, an 8.2% increase over 2015.

According to the report, ISBNs for print books rose 11.3% to 638,624 titles, while e-book ISBNs for self-publishers fell 3.2% to 148,311. Since Bowker measures the number of self-published books by ISBN, its count does not include e-books released by authors through Amazon’s KDP program, as they use ASIN identifiers rather than an ISBNs.

The 11% increase in print self-published titles was a slower gain than the 34% increase in 2015 over 2014. While the number of self-published e-books did fall in 2016, the decline was slower than the 11% drop reported in 2015.

“Overall, we believe that these numbers point toward an ongoing maturation and stabilization of the self-publishing industry,” said Beat Barblan, director of identifier services at Bowker.

You can find more info in the report (PDF) or over on PW.

The thing about this report is that it doesn’t actually mean what you think it means.

For those just tuning in, an ISBN is more or less a serial number for  a book. You must get one for a print book or it can’t be distributed, but the same is not true for an ebook (although there are benefits to getting an ISBN for an ebook).

ISBN registrations are handled by a different agency in each country. In the US, that is Bowker.

Since Bowker only license ISBNs in the US, and nowhere else, they can’t tell you the number of ISBNs registered by self-published authors in, say, Canada.

To be fair to Bowker, they implied the distinction in the actual report, but even they muffed their commentary, saying they saw “an ongoing maturation and stabilization” . Publishers Weekly missed that nuance, and many pundits are going to make the same mistake.

My point?

We have no clue how many ISBNs were registered by indie authors, much less the number of titles published by said authors, so be careful how you use this data.


Nate Hoffelder

View posts by Nate Hoffelder
Nate Hoffelder is the founder and editor of The Digital Reader. He has been blogging about indie authors since 2010 while learning new tech skills weekly. He fixes author sites, and shares what he learns on The Digital Reader's blog. In his spare time, he fosters dogs for A Forever Home, a local rescue group.


  1. Data Guy26 October, 2017

    “While the number of self-published e-books did fall in 2016…”

    Bowker once again seems to be confusing the # of self-published ebook ISBN registrations with a statistic that indicates anything meaningful about the ebook market.

    As of 2017, *most* ebook sales in the US — 52% of unit purchases each day — are of books with no associated ISBN. And that stat includes ALL ebooks, including traditionally published ones. If we’re talking indie-only, then fewer than 1 in 5 indie ebook sales in the US has an associated ISBN.

    Nowadays, ISBNs are about as useful an indicator of ebook market dynamics as attempting to track automotive trends by counting horseshoes.

  2. […] No One Knows Exactly How Many eBooks Indie Authors Published Last Year 23 October (Digital Reader) Nate Hoffelder considers Bowker’s annual report on ISBN registrations and argues that everyone is still misunderstanding the annual statistics. […]


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